Cleaning coke deposits from process equipment

Abstract

A method for cleaning a coke deposit from an internal surface of a process equipment, comprising removing at least a portion of the coke deposit from the internal surface using a flexible pig comprising a plurality of bristles, without damaging a metal protective layer of the internal surface of the process equipment. A flexible pig for cleaning a coke deposit from an internal surface of a process equipment without damaging a metal protective layer of the internal surface, comprising a flexible body formed of a polymeric material, and a plurality of bristles partially encapsulated by the polymeric material of the flexible body.

What is claimed is: 
     
       1. A method for cleaning a coke deposit from an internal surface of a process equipment, the method comprising:
 propelling a flexible pig through the process equipment, wherein the flexible pig is propelled by a fluid comprising an aqueous solution; and 
 removing at least a portion of the coke deposit from the internal surface using the flexible pig, without damaging a metal protective layer of the internal surface of the process equipment, 
 wherein the flexible pig comprises:
 at least two foam spacers, 
 at least two bristle sections, and 
 a flexible cable extending along a longitudinal axis of the flexible pig through the at least two foam spacers and through the at least two bristle sections, 
 wherein each of the at least two bristle sections comprises a plurality of bristles, and wherein the at least two bristle sections are separated by one of the at least two foam spacers. 
 
 
     
     
       2. The method of  claim 1 , wherein each of the at least two foam spacers comprises a closed-cell foam selected from polyethylene, cross-linked polyethylene, polypropylene, polystyrene, polyurethane, rubber, neoprene, copolymers thereof or combinations thereof. 
     
     
       3. The method of  claim 1 , wherein one of the at least two foam spacers is on an end of the flexible pig. 
     
     
       4. The method of  claim 3 , wherein another of the at least two foam spacers is on an opposite end of the flexible pig. 
     
     
       5. The method of  claim 1 , wherein a length of each of the foam spacers as measured along a longitudinal axis of the flexible pig is greater than a length of each of the bristle sections as measured along the longitudinal axis of the flexible pig. 
     
     
       6. The method of  claim 1 , wherein a ratio of length to diameter (L/D) of the flexible pig is from about 2:1 to about 6:1. 
     
     
       7. The method of  claim 1 , wherein the plurality of bristles in each of the at least two bristle sections are arranged in a configuration of a spiral bristle coil. 
     
     
       8. The method of  claim 1 , wherein the flexible pig has a metal protective layer on at least one of the plurality of bristles, the method further comprising:
 transferring at least a portion of the metal protective layer on the at least one of the plurality of bristles onto the internal surface of the process equipment, wherein the metal protective layer on the at least one of the bristles comprises a stannide. 
 
     
     
       9. The method of  claim 1 , wherein the plurality of bristles are polymer bristles, steel bristles, natural bristles or any combination of polymer bristles, steel bristles, or natural bristles. 
     
     
       10. The method of  claim 1 , wherein the step of removing comprises:
 placing the flexible pig in the process equipment such that the plurality of bristles of the flexible pig are in contact with the internal surface; 
 providing a fluid force against an end of the flexible pig; and 
 contacting the coke deposit with at least one of the plurality of bristles, 
 wherein a fluid source provides the fluid force of less than about 60 psig to the end of the flexible pig causing at least one of the plurality of bristles of the flexible pig to contact the coke deposit. 
 
     
     
       11. The method of  claim 1 , further comprising:
 after the step of removing, performing intelligent pigging to determine a condition of the internal surface of the process equipment; and 
 reapplying a protective metal to any portion of the internal surface having less than a threshold thickness of the metal protective layer, 
 wherein the metal protective layer protecting the internal surface comprises a stannide. 
 
     
     
       12. A flexible pig for cleaning a coke deposit from an internal surface of a process equipment, the flexible pig comprising:
 the flexible pig comprises:
 at least two foam spacers, 
 at least two bristle sections, and 
 a flexible cable extending along a longitudinal axis of the flexible pig through the at least two foam spacers and through the at least two bristle sections, 
 wherein each of the at least two bristle sections comprises a plurality of bristles, and wherein the at least two bristle sections are separated by one of the at least two foam spacers. 
 
 
     
     
       13. The flexible pig of  claim 12 , wherein each of the at least two foam spacers comprises a closed-cell foam selected from polyethylene, cross-linked polyethylene, polypropylene, polystyrene, polyurethane, rubber, neoprene, copolymers thereof, or combinations thereof. 
     
     
       14. The flexible pig of  claim 12 , wherein one of the at least two foam spacers is on an end of the flexible pig. 
     
     
       15. The flexible pig of  claim 12 , wherein another of the at least two foam spacers is on an opposite end of the flexible pig. 
     
     
       16. The flexible pig of  claim 12 , wherein a length of each of the foam spacers as measured along a longitudinal axis of the flexible pig is greater than a length of each of the bristle sections as measured along the longitudinal axis of the flexible pig. 
     
     
       17. The flexible pig of  claim 12 , wherein a ratio of length to diameter (L/D) of the flexible pig is from about 2:1 to about 6:1. 
     
     
       18. The flexible pig of  claim 12 , wherein the plurality of bristles in each of the at least two bristle sections are arranged in a configuration of a spiral bristle coil.